The Rockford Files (1974 - 1980)

Was a detective series about an ex-con private investigator. He had a natural mis-trust of the police and the legal system in general as he had been wrongly convicted of armed robbery. Luckily, new evidence proved his innocence and he was released. Often, he would get involved in closed cases that the police felt had been solved. Rockford would find evidence to suggest that the police were wrong. He also typically underestimated how difficult it would be to find the true perpetrators and to convince the police that he, not they, were correct. He wasn't the typical tough guy PI as on most other series. He would prefer to avoid a fight where possible.